An attempt to eradicate porcine reproductive and respiratory syndrome virus (PRRSV) after an outbreak in a breeding herd: eradication strategy and persistence of antibody titers in sows

A sow multiplier herd of high health status experienced an outbreak of porcine reproductive and respiratory syndrome (PRRS). In an effort to eradicate the PRRS virus, breeding animals were deliberately infected with the farm strain by exposing them to whole piglets and minced tissues of piglets that died in the farrowing crates. The herd was then closed for 23 weeks. No clinical signs were observed after the initial outbreak and there was no evidence of virus circulation in the herd verified through serological testing by PRRS ELISA, during the 2 years after the eradication attempt. Approximately one third of sows present at the time of the outbreak were still seropositive 20 months after the deliberate infection.